In communications networks, there may be a challenge to obtain good performance and capacity for a given communications protocol, its parameters and the physical environment in which the communications network is deployed.
For example, reconfigurable antenna systems (RAS) are increasingly used in wireless cellular networks to improve the network operation and communication quality. One common variant of RAS is antenna tilting which is applied to balance the coverage of a sector antenna with the interference generated to and received from neighboring cells. An antenna pattern can be tilted mechanically or electrically, by local input or using remote control. More advanced antenna pattern shaping is becoming feasible with the introduction of active antennas having integrated radio frequency functionality. For example, the beam width or sidelobe levels may be adjusted by changing the excitation of individual antenna elements within an antenna array.
In order to tune the RAS settings of many antennas and cells in a network, different automated algorithms may be applied. These algorithms are commonly denoted as RAS-SON algorithms, where SON is short for self-organizing network or self-optimizing network. Due to the complexity of predicting the network response to a considered RAS change, it is common to test the new settings and observe the changes in network behavior, and then decide, based on the performance changes, whether to keep the new settings or revert back to the original settings. Typically, a conservative approach is required in order not to have too large or too frequent performance drops by using non-optimal settings. Another mechanism to achieve a stable working network involves collecting network behavior statistics or Key Performance Indicators (KPIs) for significant time periods in order to gain confidence that the new settings indeed provide improved performance.
RAS-SON algorithms as outlined below are ill-suited to cope with rapid changes in the network. One particular case of a rapid change in the network is the loss of a cell due to e.g. power outage. When such an outage occurs, the network needs to readjust its RAS settings quickly to mitigate, or even avoid, service loss, which is contradicting to the slow and conservative approach outlined above.
Hence, there is still a need for an improved determination of antenna settings in a wireless communications network.